3,156 research outputs found
Dynamics of inelastically colliding rough spheres: Relaxation of translational and rotational energy
We study the exchange of kinetic energy between translational and rotational
degrees of freedom for inelastic collisions of rough spheres. Even if
equipartition holds in the initial state it is immediately destroyed by
collisions. The simplest generalisation of the homogeneous cooling state allows
for two temperatures, characterizing translational and rotational degrees of
freedom separately. For times larger than a crossover frequency, which is
determined by the Enskog frequency and the initial temperature, both energies
decay algebraically like with a fixed ratio of amplitudes, different
from one.Comment: 5 pages, RevTeX, 2 eps figures, slightly expanded discussion, new
figures with dimensionless units, added references, accepted for publication
in PRE as a Rapid Com
Breakdown of Energy Equipartition in a 2D Binary Vibrated Granular Gas
We report experiments on the equipartition of kinetic energy between grains
made of two different materials in a mixture of grains vibrated in 2
dimensions. In general, the two types of grains do not attain the same granular
temperature, Tg = 1/2m v^2. However, the ratio of the two temperatures is
constant in the bulk of the system and independent of the vibration velocity.
The ratio depends strongly on the ratio of mass densities of the grains, but is
not sensitive to the inelasticity of grains. Also, this ratio is insensitive to
compositional variables of the mixture such as the number fraction of each
component and the total number density. We conclude that a single granular
temperature, as traditionally defined, does not characterize a multi-component
mixture.Comment: 4 pages, 5 figures, submitted to Physical Review Letters, updated
reference
Application of cmOCT and continuous wavelet transform analysis to the assessment of skin microcirculation dynamics
In-vivo assessment of microvascular functional dynamics by combination of cmOCT and wavelet transform
Detecting Star Formation in Brightest Cluster Galaxies with GALEX
We present the results of GALEX observations of 17 cool core (CC) clusters of
galaxies. We show that GALEX is easily capable of detecting star formation in
brightest cluster galaxies (BCGs) out to and 50-100 kpc. In most of
the CC clusters studied, we find significant UV luminosity excesses and colors
that strongly suggest recent and/or current star formation. The BCGs are found
to have blue UV colors in the center that become increasingly redder with
radius, indicating that the UV signature of star formation is most easily
detected in the central regions. Our findings show good agreement between UV
star formation rates and estimates based on H observations. IR
observations coupled with our data indicate moderate-to-high dust attenuation.
Comparisons between our UV results and the X-ray properties of our sample
suggest clear correlations between UV excess, cluster entropy, and central
cooling time, confirming that the star formation is directly and
incontrovertibly related to the cooling gas.Comment: 39 pages, 11 figures; accepted for publication in The Astrophysical
Journal. Figure quality reduced to comply with arXiv file size requirement
Revealing the velocity structure of the filamentary nebula in NGC 1275 in its entirety
We have produced for the first time a detailed velocity map of the giant filamentary nebula surrounding NGC 1275, the Perseus cluster’s brightest galaxy, and revealed a previously unknown rich velocity structure across the entire nebula. These new observations were obtained with the optical imaging Fourier transform spectrometer SITELLE at CFHT. With its wide field of view ( ∼11 arcmin × 11 arcmin), SITELLE is the only integral field unit spectroscopy instrument able to cover the 80 kpc  ×  55 kpc ( 3.8 arcmin × 2.6 arcmin) large nebula in NGC 1275. Our analysis of these observations shows a smooth radial gradient of the [N II]λ6583/H α line ratio, suggesting a change in the ionization mechanism and source across the nebula. The velocity map shows no visible general trend or rotation, indicating that filaments are not falling uniformly onto the galaxy, nor being uniformly pulled out from it. Comparison between the physical properties of the filaments and Hitomi measurements of the X-ray gas dynamics in Perseus is also explored
Developing and sustaining specialist and advanced practice roles in nursing and midwifery: A discourse on enablers and barriers
Aims and objectives
To collate, synthesise and discuss published evidence and expert professional opinion on enablers and barriers to the development and sustainability of specialist and advanced practice roles in nursing and midwifery. Background
Expanded practice is a response to population health needs, healthcare costs and practitioners’ willingness to expand their scope of practice through enhanced responsibility, accountability and professional autonomy. Design
This discursive paper is based on a rapid review of literature on enablers and barriers to the development and sustainability of specialist and advanced practice roles and is part of a wider policy analysis. Methods
We analysed and synthesised of 36 research articles, reviews and discussion papers on enablers and barriers in the development and sustainability of expanded practice roles. Results
Several factors enable role expansion, including: role clarity; credentialing and endorsement; availability of education for expanded roles; individual practitioners’ dispositions towards role expansion; support from peers, other professionals and the work organisation; and costs. Where limited or absent, these same factors can constrain role expansion. Conclusions
Enabling nurses and midwives to practice to their full scope of education and expertise is a global challenge for disciplinary leadership, a national challenge for professional regulation and a local challenge for employers and individual clinicians. These challenges need to be addressed through multistakeholder coordinated efforts at these four levels. Relevance to clinical practice
This discursive paper synthesises empirical evidence and expert professional opinion on the factors that enable or hinder the development and sustainability of specialist and advanced practice roles. Providing a critical appraisal of current knowledge, it provides a reference source for disciplinary debate and policy development regarding the nursing and midwifery resource and informs clinicians of the myriad issues that can impact on their capacity to expand their scope of practice
Granular cooling of hard needles
We have developed a kinetic theory of hard needles undergoing binary
collisions with loss of energy due to normal and tangential restitution. In
addition, we have simulated many particle systems of granular hard needles. The
theory, based on the assumption of a homogeneous cooling state, predicts that
granular cooling of the needles proceeds in two stages: An exponential decay of
the initial configuration to a state where translational and rotational
energies take on a time independent ratio (not necessarily unity), followed by
an algebraic decay of the total kinetic energy . The simulations
support the theory very well for low and moderate densities. For higher
densities, we have observed the onset of the formation of clusters and shear
bands.Comment: 7 pages, 8 figures; major changes, extended versio
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